- The files and paths point to valid locations (run the “UseHomePaths” macro)
- The slot numbers entered in the Startup panel match the location of the modules.
- The correct drivers are used (version 6.5.0) and modules are recognized in
Window’s Device Manager as shown above
7.
After starting up modules, the Oscilloscope traces show only rectangular waves.
This problem can be caused by downloading the wrong Communication FPGA file
(e.g. a Rev. B file to a Rev. C module). Verify the file names are correct.
8.
Module boots ok and shows Oscilloscope traces, but MCA spectra can not be
read (error about DMA transfer).
In some cases, Windows 7 administrator privileges are required to properly execute
DMA transfers (e.g. spectrum readout). Even on a Windows user account with
administrator priviledges, it may be required to specifically start Igor Pro as
administrator (find "Igor" in the Windows Start Menu, right click, select "run as
administrator", then open the Pixie Viewer from Igor via File -> Open -> Pixie4.pxp).
9.2 Acquisition Problems
1.
Signal from PMT shows unusual pulse shape
Verify the input jumpers are set to the correct termination. When taking the signal
directly from the PMT without a preamplifier, the correct termination is usually 50Ω
2.
Missing peaks in spectra
3.
Unusually low count rate
4.
Unusually low Live Time
Open the O
SCILLOSCOPE
and verify that the signal is in range, i.e. that large pulses are
not cut off at the upper end of the range (16K) and that the baseline is above zero
5.
Low efficiency for high energy peaks in MCA spectrum
At high rates, pulses overlap with the decaying tail of a previous pulse. When two or
more pulses overlap in this way, higher energy pulses are more likely to go out of
range
=> reduce gain and/or adjust the offset
If the detector output shows significant ringing or overshoots, it can happen that the
Pixie-4 triggers twice on the same pulse (first on the rising edge, then on the
overshoot). This would be more likely for higher energy pulses, because the ringing
or overshoot has a larger amplitude.
=> increase the trigger threshold and/or the trigger filter rise time or use the advanced
options to “pause” or (for low count rates) disable the pileup inspection.
6.
Data collection in list mode has low DAQ fraction
7.
SFDT is a large fraction of the live time